You are likely better off asking this question on an SPSS forum. I suspect we do not have a lot of people here that know much about SPSS and especially about R extensions for SPSS.
I know I have not used SPSS in many years. I keep being surprised it still exists.
If the data is not confidential or you can give use some simulated data either in Excel or in . csv form, (stick the Excel file on something like Dropbox) and provide your R code here we may be able to walk you through using R.
See, for general suggestions:
FAQ Asking Questions
For .csv format out put the data to a .csv file Copy the output and paste it here between
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Sorry to not be of more help.